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Evidence-Based Practice Research in Nursing

Information and resources for research in Evidence-Based Practice

Study Types

Systematic Review Summarizes the results of a systematic literature search on a specific clinical question to develop clinical recommendations. The studies are reviewed, assessed, and the results are summarized according to the predetermined criteria of the review question. They assess the methodology, sample size, and quality of the studies, using the highest quality data available to answer specific clinical questions and develop practice recommendations.

Meta-Analysis Takes the above process one-step further, reviewing a clinical question for which multiple systematic reviews exist and combining all the results using accepted statistical methodology .

Randomized, Controlled Clinical Trial - A prospective, analytical, experimental study using primary data generated in the clinical environment. Individuals who are similar at the beginning are randomly allocated to two or more groups (treatment and control) and the outcomes of the groups are compared after sufficient follow-up time.

A study that shows the efficacy of a diagnostic test is called a prospective, blind comparison to a gold standard study. This is a controlled trial that looks at patients with varying degrees of an illness and administers both diagnostic tests -- the test under investigation and the "gold standard" test -- to all of the patients in the study.

Cohort Studies Identify a large population which already has a specific exposure or treatment, follows them over time (prospective), and compares outcomes with another group that has not been affected by the exposure or treatment being studied. Cohort studies are observational and not as reliable as randomized controlled studies, since the two groups may differ in ways other than in the variable under study.

Case Control Studies Studies in which patients who already have a specific condition or outcome are compared with people who do not. Researchers look back in time (retrospective) to identify possible exposures. They often rely on medical records and patient recall for data collection. These types of studies are often less reliable than randomized controlled trials and cohort studies because showing a statistical relationship does not mean than one factor necessarily caused the other.

Case Series and Case Reports Collections of reports on the treatment of individual patients or a report on a single patient. Because they are reports of cases and use no control groups with which to compare outcomes, they have no statistical validity.

Background Information / Expert Opinion Use varied evidence to present information that ranges from expert opinion to providing summaries of well-known information with established evidence. They are good resources to begin understanding a topic, learning definitions, and clinical parameters. However, when answering an EBP question, look for information with statistically significant data from resources higher-up in the pyramid.

Adapted from: Duke University Medical Center Library: Evidence-Based Medicine Resources

Study Terminology

Research studies often contain language that may be unfamiliar to nurses. Some of the basic terminology commonly found in research studies are listed below:


Abstract: A brief summary or overview of the research study.

Case Study: A collection of detailed information about a person or specific group.

Causality: The relationship between the cause and effect of a situation or event.

Consent: An agreement given by a competent person to participate in a research study.

Control Group: Randomly selected participants from the research group who won't receive the experimental treatment or variable. Those in the control group will be compared with those receiving the treatment or variable under investigation to establish the effectiveness or ineffectiveness of the variable/treatment.

Double-Blind Study: A research study conducted in which neither the investigators nor the participants know specific details of the study, such as whether a placebo or trial medication is being administered.

Experimental Research Group: Randomly selected participants from the research group who will receive the experimental treatment, medication, or variable.

Hypothesis: An educated guess about the expected outcome of a study.

Mean: The average score between two variables or outcomes.

Single-Blind Study: A research study conducted in which the investigators know specific details of the study but the participants don't.

Variable: An intervention, action, or medication that's being studied to observe its effect on the research group. For example, a group of oncology patients may receive a new cancer medication to study its effectiveness on reducing tumor cell growth. In this scenario, the new medication is the intervention or variable.

Source: Chrisman, J., Jordan, R., Davis, C., & Williams, W. (2014). Exploring evidence-based practice research. Nursing Made Incredibly Easy, 12(4), 8–  12.